Drilling risers are employed while drilling an offshore well. The drilling riser extends from a subsea wellhead on the sea floor to a drilling platform on the surface. A typical drilling riser has a central riser pipe and a number of auxiliary pipes or lines. The operator rims drill pipe, casing, and various tools through central pipe of the riser. The auxiliary lines are parallel to the central pipe, spaced around it, and have smaller diameters. The operator supplies hydraulic fluid through some of the auxiliary lines and employs others as choke and kill lines.
Normally, drilling risers utilize buoyancy to reduce the overall weight of the components in water. One type of buoyancy comprises modules of buoyant material. The modules push upward on the riser couplings while in water due to the buoyancy. While in air, the weight of the modules transfer to the riser couplings. The modules tend to move upward while in water, and this movement is resistant by a variety of devices. The devices may be complex or use friction to resist the upward movement. These devices also include thrust columns that have adjustment notches.